It is known to ventilate a rotating cavity by supplying an axial through-flow of air, which is cooler than the disc drums of turbines or compressors. This axial through-flow of air is inherently unstable and complex flow patterns are set up in the cavities that make heat transfer effects very difficult to quantify and reduces cooling efficiency. To partially remedy this problem, it is also known to introduce a radially inward through-flow into the cavity, and subsequently heat transfer in the cavity is both enhanced and made more predictable, but is still not sufficiently accurate.
Where accurate prediction and maximised cooling is available it is possible, in the case of a compressor rotor, to improve component lives, enable the use of cheaper materials, have a better control of blade tip clearances and hence improve thermodynamic efficiency and operability.
Therefore, the object of the present invention is to provide an improved cooling arrangement for the cavities between rotors in turbine and compressor assemblies of gas turbine engines.